1. Technical Field
The present disclosure relates to semiconductor nanostructures, and particularly to a two-dimensional semiconductor nanostructure.
2. Description of Related Art
In the past few decades, transistors are continuously scaled down in size, which has led to significant improvements in the field of miniature semiconductor electronic devices. Presently, the metal oxide semiconductor field effect transistors (MOSFETs) have been scaled down to the nanometer scale. Unfortunately, varieties of problems emerge when the size of MOSFETs approaches the nanometer scale. One of these problems is that carrier (electron and/or hole) mobility of semiconductor nanostructures in MOSFETs becomes low when the size of MOSFETs is reduced. Currently, the semiconductor nanostructures in MOSFETs are made of film shaped silicon. An approach for increasing the carrier mobility is commonly carried out by introducing an appropriate strain to change the dimensions of the lattice. The energy bands of the semiconductor nanostructures are changed with respect to the changes of the dimensions of the lattice, and the changes of the energy bands may increase the carrier mobility. However, in the approach above, impurity scattering that restricts the carrier mobility is not taken into account. The impurity scattering means that carriers can scatter as they travel through the impurity atoms. In detail, as the carriers travel through impurity atoms, a Coulomb interaction generates between the carriers and the impurity atoms. Therefore, the carriers and the impurity atoms can be mutually attrahent or exclusive, such that the motion directions of the carriers change, thereby decreasing the carrier mobility.
As disclosed by a prior art, the impurity scattering phenomenon in doped one-dimensional silicon nanotubes is not obvious. The nonuniformity of wall thickness of the silicon nanotubes can cause quantum confinement effect. The carriers are located in the thicker wall of the silicon nanotubes. N-type or P-type doping elements for increasing the concentration of the carries (e.g., electrons or holes) are confined in the thinner wall. Thus, the doping elements and the carriers are spatially separated from each other, such that the impurity scattering phenomenon is reduced, thereby increasing the carrier mobility.
However, the reduction principle of the impurity scattering in the one-dimensional silicon nanotubes cannot be applied for reducing the impurity scattering in a two-dimensional semiconductor nanostructure. Therefore, it is not an approach for decreasing the impurity scattering of the two-dimensional semiconductor nanostructure.
What is needed, therefore, is to provide a two-dimensional semiconductor nanostructure having relatively high carrier mobility due to reduction of the impurity scattering.